Generally, the arrangement of the incoming and outgoing lines of the power inductor is single in and single out with copper foil or litz wire. When the arrangement is single in and single out, it is not cost-effective in the application of high power UPS or high power inverter, since the inductive current will be very high and have to be measured by a current sensor with a large measuring range. If using multiple independent insulate flat conductors or using litz wires, the proportional shunting would not be accurate because of skin effect and proximity effect which are hard to overcome, and therefore it would be hard to implement shunting measurement and the cost of material and winding would be very high.